During container processing, a container encounters different machines that perform different tasks. Examples of machines include sterilizing machines, feature detectors, and printers. It is therefore necessary to somehow convey the container from one machine to the next.
For certain applications, it is important that the container retain a precise alignment. For example, when printing a multi-colored image on a container, the container must go through several printing machines, each of which prints a different color. The resulting printed image is a superposition of several printed images, each one in a different color.
The container must be brought from one printer to the next so that each color can be printed. Moving containers from one printer with next creates opportunity for error. When arriving at a new printer, the container must be correctly aligned. Otherwise the second colored image will not sit directly on top of the first.
Precise alignment is necessary for other tasks. For example, when detecting a feature on a container, it is important to have the feature in a place at which it can be seen. In a labeling machine, a misaligned bottle may find itself with a label at the wrong location.